James a



UNITED STATES, PATENT OFFICE,

FRANK G. BREYER, OF PALMERTON,PENNSYLVANIA, JAMES A. SINGMAS'IEE, OF

BRONXVILLE, NEW YORK, AND ALBERT E. HALL, 'OF PALMEBTON, PENN- SYLVANIA,ASSIGNORS TO THE NEW JERSEY ZINC COMPANY, OF NEW YORK, N. Y., ACORPORATION OF NEW JERSEY.

PRODUCTION OF METAL OXIDS OTHER COMPOUNDS OF METALS.

No Drawing.

To all whom it may concern:

Be it known that we, FRANK G. Banner, a citizen of the United States,residing at Palmer-ton Carbon county, State of Pennsylvania, JAMES A.Smomas'rna, a citizen of the United States, resldmg at Bronxvllle,

\Vestchester county, State of New York,- and ALBERT E. HALL, a citizenof the United States, residing at Palmerton, Carbon county, State ofPennsylvania, have ini'ented certain new and useful Improvements in theProduction of Metal Oxids and other Compounds of Metals; and we dohereby declare the following to be a full, clear, and exact descriptionof the invention, such as will enable others skilled in the artto whichit appertains to. make and use the same.

This invention relates to the production of metal oxide or othercompounds of metals volatilized by the l/Vethcrill process.

Metallic oxids, such, for example, as zinc oxid and loaded zinc oxid. aswell as other iompoundsof metals volatilized by the Wetherill process,such, for exam le, as basic lead sulfate or sublimed lead haveheretofore been more or less extensively produced by the so-calledWetherill process.

In speaking of metals volatilized by the VVetheiill process, we intendto describe and cover such metals as are volatilizable at thetemperatures attainable in the Vetherill process, and for the sake ofbrevity, we shall hereinafter designate these metals as Volatilizablemetals. In the case of certain of such metals, the final or desiredcompound or compounds thereof are the result of a sequence of actions inwhich the metalliferou",

materials of the charge are reduced, the reduced metal yolatilized andthen oxidized or otherwise compounded, while in other cases a metalcompound may be directly volatilized, with or without. subsequent 0X1-dation or compounding. o

By the expression Wetherill process as we have used the same herein,is'tobe understood the furnacin'g step'of the process for producingmetal oxide or other compounds of volatilizable metals in which a chargeof the metalliferous' material mixed with a reducing agent and spread.on an ignited bed of fuel is subjected to a combustion supporting blastor draft and Specification of Letters Patent;

Application filed August 1, 191a. Sena-m. 314,721.

brought to a sufiiciently high ten'iperature to reduce the metalliferousmaterials and volatilize the reduced metal or metals (and (or) tovolatilize a metal or a metal cont: pound or compounds) without bringingthe charge to a condition where it becomes impervlous to the blast ordraft, the entire charge being supported ona furnace hearth or grate'designed to hold it without letting part drop through, and

any considerable the work-oil material being discharged as a clinker orsinter. The furnacing step is independent of the subsequent treatment ofthe laden furnace gases and of the collection of the metal compound orcompounds.

As a typical example of the Wetherill process, as heretofore usuallypractised, we

will briefly describe the customary procedure in the commercialproduction of zinc oxid, including leaded zinc oxid. -The fur-. nacingstep is generally carried out. in a furnace having a broad expanse ofhorizontal grate or hearth roofed over with an arch, and associated withappropriate instrumentalities for permitting the passage therethroughand into the charge, by either a blast or draft, of a combustionsupporting gas. It is customary to first charge upon the furnace grateor hearth a layer of buckwheat anthracite coal (which is thereuponignited, usually by the residual heat of the furnace) and by means of aforced blast or with the finely divided zinkiferous (or zinkiferous andplumbiferoi'ls) material,-

such as zinc silicate, roasted zinc blends, roasted so-called mixedsulfids of zinc and lead, spelter retort residues, or other reduciblezinc-containing or zinc-andlead' containing material at the disposal ofthe.

operator. 3} The forced air draft is continued, and, when the familiarflames of greenish tint, known as zinc candles, begin to maketheirappearance above the upper surface #0 ,theeharge, indicating that I therecluctionf.-and volatilization of the zinc and its oxidation to theform oi fame is well under way, the products of combustion carrying thezinc oxid fume and other. volatilized metallic compounds are conveyedthrough the customary cooling flues, etc., to tlfie ba -room wherein ina cooledcondition, t e

intd the atmosphere, leaving the fume collected in the interior of thebags, from which it is removed at convenient intervals.v The furnaceoperation is continued until the production of fume therefrom inappreciable quantity ceases, whereupon the residual charge which is, toa large extent, sintered together, is broken up by long-handled rabblesand pried up and lifted or scraped out through the furnace doors into areceiving pit, or the like, preparatory to the starting of a newoperation. The coal or other carbonaceous material of the charge servesthe two-fold purpose of furnishing a reducing agent for effectin thereductlon of the metalliferous materiais of the charge and offurnishing, by com ustion, the necessary degree of heat to bring thesematerials to the reducing temperature characteristic of the process.

As thus ordinarily practised, the abovedescribed furnace operation isattended with certain defects interfering with its full efliciency.Prominent among these defects is the inevitable tendency to theformation of blow-holes or craters at various regions of the charge.These blow-holes represent severally the paths of least resistance forthe blast in its passage through the charge and to the extent to whichthey develop in p the progress of the operation they interfere with theuniform distribution of the air in its upward passage and produce hot,spots representing excessive temperatures as comared with other regionsof the charge.

rom time to time, the workmen endeavor to eliminate these blow holes orhot spots, as far as is feasible, by rabbling the upper surface of thecharge, thereby filling in the blow holes or breaking up theircontinuity;

but in spite of the palliative effect of these expedients (which,moreover, consume considerable of the workmans time and attention), itis im ossibl'e to obtain uniform working conditions throughout theentire extent of the charge; so that there is not only waste of fuel,and the production 10- cally of higher temperatures than is ,desirable,but the residues taken from the furnace at the termination of theoperation contain.

eisen furnace, it interferes to a greater, or-

ter through the bags and pass offless extent with-the normal furnaceoperation and tends to collect in and obstruct the spiegeleisen furnaceflues.

A further defect of the above-described furnace'practicevis that theforced draft, which is employed under relatively considerable pressure,tends to project into the free space above the charge more or less dust,particularly in the region of the blowholes referred to, and thisdusting is further aggravated by the rabbling operations; consequently,in addition to the metallic fume, the products of combustion carry withthem from the furnace a notable proportion of dust in the form of fineparticles of unreduced ore, carbon, ash, and the like, which tend tocontaminate the fume proper-and damage its color and marketability.

There are, furthermore, certain requirements of the practice of theWetherill rocess as heretofore conducted which hamper the operator inthe selection of the qualit and size both of the coal and of the zinkierous material employed in making up the charge. Thus, the requirementthat the charge shall be sufficiently permeable for the passage of theair, necessitates the use of a mixture of coal and zinkiferous materialof a fairly coarse "grader Serious difficulties are encountered in theuse of the smaller sizes of buckwheat coal; and only a fractional partof the zinkiferous constituents of the charge can consist of suchextremely finely-divided materi s as flotation concentrates, zincprecipitate flue-dust containing zinc, or the-like. Q

The present invention is designed to improve the practice of theWetherill process, particularly in the respects noted. .That 1s to say,to obtain a more uniform distribution of the combustion supporting as onits .way through the charge; to lower t e resistance of the charge tothe passage of the gas; to avoid the formation of blow holes or hot 5ots; to minimize the contamination of the ume by dust; to increase thepermissible quantity of the working charge and consequently the amountof metalliferous material treated in a given time period; to obtain amore complete extraction of the volatilizable metal values and a savingof fuel per unit of metalliferous material present; to eflectively emloy cheap coal of extremely small mesh an coal of such low grades ascolliery washings, coke breeze, and the like; and to freely utilizemetalliferous material of any degree of fineness, including flotationconcentrates, finely pulveru- .lent ore, metalliferous precipitates,flue dust, etc.

For the attainment of the improved results referred to, we haveradically modified the present commercial practice of the Wetherillprocess. Thus, for the initial step of charging the grate bottom orhearth coal below the No. 3 buckwheat size,such

pressing finely divided coal, suitable binder (preferably of the usualoxid furnace with a layer of fine ignition fuel, we have substituted alayer or bed of ignition fuel in the form of briquets. We have found, inactual practice, that it is feasible to employ as the ignition or bedfuel, briquets prepared by comtogether with a the concentrated wastesulfite liquor of the sulfite paper pulp industryfiyand that the coalappropriate for the purpose may consist of the cheaper and smallergrades, as, for instance, anthracite as No. 4 buckwheat, collierywashings (dirt coal or dust coal), coke breeze, etc. We have found that,for this ignltlon or bed fuel, it is suitable to employ briquets of suchsize and shape as ,duce the resistance to the combustion supporting gas,and nevertheless to supply such a substantially uniform sub-stratum forthe support of the superposed working charge as to give free access andpractica ly equal distribution of the gas thereto. Thus, the

to materially reignition or bed fuel briquets may be made 9f a formapproximating two pyramids havng a common rectangular base of say 1%inches on each side, the thickness of the briquets from the apex of onepyramid to the other being say 1% inches. In general,

' the fuel briquets should be. of substantially bution of the ignitionuniform size, and preferably of such shape that theyroll or tumbleeasily over one another. We have found the so-called pillow block,eggette, rounded pillow block, overstufl'ed pillow, and similar shapeswell suited to the purposes ofthe invention. We have ascertained thatwhen, instead of the usual layer of buckwheat anthracite coal, alayer orbed of these fuel briquets is charged upon the grate bottom or hearth ofthe usual oxid furnace as ignition fuel, the briquets will becomeignited by the residual heat of the preceding charge and that theymaythen be brought to well developed'combustion, the Working charge may besupplied, without substantially disturbin the orginal distriiriquets,and, consequently, with the preservation of the fairly uniform gaspassages which the i ition briquets provide over the entire sur ace ofthe hearth for the upward passage of'the blast into. the working charge.In some instances, such a percentage of metalliferous material may beincorporated in the ignition briquets as may be tolerated withoutsubstantially interfering with their normal function, and to the extentto which this is permissible, the ignition briquets will add a reducingfunction to their normal ignition function, i

A second, characteristic feature or the invention consists in making upthe working (that is to say, the re- 7 the anthracite dust or slushcoal,

without briqueting the reducing agent charged withit; or bybriquetingthe reducing agent and not briquet'ing the metalliferousmaterial .or by briquetmg the reducing agent and briqueting themetalliferous material separately therefrom; or, preferably by briquetine, mixture of and of t ef'inhtalliferorm material. These briquets may bemade of the same shape and dimensions as the fuel briquets hereinbeforereferred to, and by the employment ofan'y suitable binder, such as theconceintrated wastesulfite liquor described. The -reducing agentemployed may be of any suitable kind, but one of the marked advantagesof the briqueting is that it permits, as we have ascertained, theeffective and economical use of reduction coal of the cheaper grades andfiner mesh, such as anthracite coal of finer mesh than No. 3buckwheancolliery washings, coke breeze, and the like,

A. typical procedure, in the manufacture of zinc oxid or leaded zincoxid, for the pros duction of the working charge briquets made from thepreferred mixture of reduction coal and zinkiferous or zinkiferous andplumbiferous material is as follows:

The reduction coal (as, for instance, anthracite dust or slush) whichusually averages from 65-7 which usually has a; moisture content ofabout 10%) is placed, together with the sulfite liquor, in a revolvingmixer of the kind employed for the mixin of concrete and, after a shortperiod of mixing, the zinkiferous (or zinkiferous and plumbiferous)material is added, and the mixin operation then continued for a furtherperiod of three minutes ormore. Thus,.for-800 pounds of 67 po'unds ofconcentrated Waste sulfite liquor of 30 Baum is employed, and themetalliferous material added may, for example, consist suitably of 960pounds of finely crushed zinc ore averaging say 20% of zinc oxid and'l6%silica, together with 480 pounds of so-called dust ore averaging say 23%of zinc oxid and 8 to 9% silica,these ores of carbon (and being, in thisinstance, mixtures consisting when the material is fed into'the pans ofthd rolls from above, it is molded into briquets havin the shape anddimensions hereing of heavy sheet iron and the bottoms of J; inch wiremesh. In these baskets, or in similar receptacles, we dry and bake thebriquets, as, for instance, by mounting the baskets filled withbriqi'ets upon buggies carrying say twelve baskets in four tiers ofthree baskets each, which are then pushed into a tunnel drier of thedirect coal-fired type. The briquets remain in the drier from one to twohours, at a temperature of approximately 200 C. dependent upon the rateof firing. The dried briquets are then removed from the drier, cooledand stored, under cover, for subsequent use. This drying and baking ofthe briquets is of service to impart to them the desirable amount ofresistance to crumbling and breaking, so that they may be freelysubjected to the rough handling incident to storin them, conveying themto the furnace, and incident to charging them into the furnace'either byhand or otherwise. and so that they may likewise substantially maintaintheir form during the period that they are giving ofl' theirvolatilizable metals in the furnace.

While some of the advantages of the invention may be attained bybriqueting either the reducing agent or the metalliferous material (orboth of them) separately, our preferred practice as above noted, is tomake the briquets of a mixture of the reducing agent andthe'metalliferous material. So also, while the working charge, partly orwholly briqueted, may'be used in conjunction with an ignition layer offine anthra cite coal, we prefer to use briqueted ignition fuel inconjunction with a briqueted working charge made up of a briquetedmixture of reducing agent and metalliferous material.

Thus, we have found that when, as in our preferred practice, the workingcharge, in-

the form of briquets made up of a m xture of' metalliferous material andreducin agent, is charged upon a layer of bed fue briquets of like shapeand ,dimensions, all of the advantages hereinbefore recited as incidentto the invention are present 'In other words, the supplying of theworking charge of briquets upon the sub-stratum of well ignitedignition-or bed fuel briquets in full combustion builds up within thefurnace a total charge of such low resistance to the upward passage ofthe combustion supporting gas, that the pressure of the blast in the ashpit may be very materially lowered; or, in some cases, it may besupplanted by the suction efi'ect of the ordinary exhaust fan employedin the \Vetherill process for withdrawing the fume from the furnace,this exhaust sufiicing to pull through the charge a sufiicient volume ofgas appropriate for the operation.

The process proceeds, wlthout the production of craters or hot spots andwith an even distribution of the combustion supporting as over theentire extent of the char c. It is also found that the reduction an-(or) volatilization of zinc, lead, and other volatilizable metalliccompounds, as well as the subsequent oxidation and recovery of fume,proceed more completely than in the here- "tofore customary practice ofthe Wetherill process, and that the residues show a materially lessenedloss of volat-ilizable metal values.

As a typical instance of the pract1ce of the invention, in the roductionof zinc oxid, 900 pounds of bed uel bri uets (which may consist entirelyof dust coal) are spread out as evenly as possible upon an oxidfurnaceygrate of 111 square ft. area. These entit es are then ignited bythe residual'heat of the furnace from a former operation, and when theyhave reached a good yellow heat, we charge upon them 8,000 pounds ofbriquets made from the m xture of reducing coal and zinkiferousmaterlal.

A much lighter blow is used, as the process proceeds, than with theheretofore usual Wetherill process charge. The res dues are withdrawn infrom 6 to 12 hours, the 8 hour period usually 'ving the best results.The same number 0 operators is used for wlthdrawing the residues as forthe heretofore that for the samelabor the charge treated may b thepractice of the invention be increase one-third. It is also found thatthe clinker adheres with very much less tenacity to the furnace walls,so that the exertion required for breaking up the clinker and removin itfrom the furnace is correspondin 1y ess arduous.

e have 'hereinbefore referred to the in- .creased capacity of outputincident to the".

invention; and, in this connection, we may state that in the preferredpractice of the in,

expenditure of fuel, to obtain a higher extraction of'volatilizablemetal values (leaving less volatilizable metals in the residue) than inthe heretofore customary Wetherill process practice, and that for afurnace run of the same time-period normally employed in working oil thecharge of the usual oxid furnace, we have been able as herein-beforeparticularly noted, to treat a briqueted charge containing as high asone-third more of metalliferous material than is contained in theheretofore customary Wetherill process working charge.

It will,- of course, be understood that the specific examples of typicalmeans of practising the inyention are to be understood as illustrativeof its practical ap lication, and that they may be widely varied withoutdeparting from the intended scope. of the invention as more broadly setforth in the general description and in the claims hereunto annexed.

While we have hereinbefore specifically described the invention byreference to the production of zinc oxid, including leaded zinc onid, weWish it to be understood that the invention is applicable to theproduction.

I of other metal compounds of the volatilizable metals. In particular,we contemplate the production oi basic lead sulfate or sub limed lead bythe method of the invention. 8U

ln general, the procedure for the production of sublimed lead issubstantially the same as hereinbefore described, substitut- Elli all

lid

.till

ing, of course, an appropriate plumbiferous material for the.zmlrlferous material.

Thus, for example, the bed fuel or the work.

ing charge or both may be briqueted in the manner hereinbefore describedand supplied to the turnace hearth in the form of briquets. The workingcharge consists of a mixture of finely divided galena or native leadsulfid and carbonaceous material or other suitable reducing agent,preferably briqueted as hereinbefore described. The

working charge is spread on the ignited.

layer of bed fuel briquets and upon reaching thu reaction temperature,the lead sulfid is reduced and (or) volatilized and subsequentlyoxidized to lead sulfate and lead o-xid thus forming the so-called basiclead sulfate.

The efiluent contain-in the sublimed lead is Withdrawn from the rnaceand the metallic product collected in any appropriate manner. As thesource of plumbiferous material, we may use a highgrade cl native leadsudfid suitably crushed and jig-god to free it from accompanyinggangue'material, or we may use lea sullid concentrates, such asflotation concentrates, or other appropriate plumbiferous-containingmaterial. with proper additions of sulfur in the form of pyrite, galena,brimstone or other suitable sulfur-carrying agents, whenever there is alaclr of sulfur in the charge to properly sulfate the fume.

What we claim is.:-'- 1. In the production by the Wetherill process ofmetal oxids or other compounds of volatilizable metals, the step ofsupplying the bed fuel to the furnace hearth in the form of briquets,substantially as described.

2. In the production by the Wetherill process of metal oxids or othercompounds of volatilizable metals, the step of supplying the bed fuel tothe furnace hearth in. the

form of briquets, said bri'quets containing a percentage ofmetalliferous material; sub stantially as described.

\3. In the production by the *Wetherilb process of metal oxide or othercompounds of volatilizable metals, the step of supplying in the workingcharge briqueted metalliferone material; substantially as described.

l. In the production by the Wetherill process of metal oxids or othercompounds of volatilizable metals, the step of supplying in the workingcharge briqueted reducing vmaterial; substantially as described. I

In the production by the 'Wetherill charge briqueted metalliferousmaterial;

substantially as described.

' '6. In the production,- by the lZVetherill process of metal oxids orother compounds of volatilizable metals, the step of supplying the bedfuel in the form of briquets, together with the step of supplying in theWorking charge briqueted reducing material; substantially as described.

8. ln the production by the Wetherill process of metal oxids or othercompounds of volatilizable metals, the step of supplying the bed fuel inthe form of briquets, together -with the step ct supplying in theworking charge a briqueted mixture of metalliferous material andreducing agent; substantially as described.

9. In the production by the Wetherill process of metal oxide or othercompounds of volatilize-hie metals, the step of supplying the bed fuelin the form of briquets, said briquets containing a percentageofmetalliferous material, together'with the step of supplying in theworking charge briqueted metalliferous material; substantially asdescribed. I

10. In the production by the Wetherill process of metal oxide or othercompounds of volatilizable metals, the step of supplyin the bed fuel inthe form of briquets, saic bri nets containiea-a ercentaae of metallsupplying v 11. In the production by the Wetherill process of metaloxids or other compounds of volatilizable metals, the step of supplyinthe bed fuel in the form of briquets, sai briquets containing apercentage of metalliferous material, to ether with the step ofsupplying in the wor 'ng charge a briqueted mixture of metalliferousmaternal and reducing agent; substantially as described.

12. In the production of sublimed lead by the WVetherill process, thestep of supplying the bed fuel to the furnace hearth in the form ofbriquets; substantiall as described. 13. In the production of su limedlead by the We'therill process, the step of supplying the bed fuel tothe furnace hearth in the formof briquets, said briquets containing apercentage of plumbiferous material; substantially as described.

14. In the roduction of sublimed lead by the Wetheril process, the stepof supplying in the working charge briqueted plumbiferous material;substantially as described.

15. In the roduction of sublimed lead by the Wetherilfprocess, the stepof supplying in the working charge a briqueted mixture of plumbiferousmaterial and reducing agent; substantially as described.

16. In the production of sublimed lead by theWetherill process, the stepof supplying the bed fuel in the form of briquets, together with thestep of supplying in the working charge briqueted :plumbiferousmaterial; substantially as described.

17 In the roduction of sublimed lead by the Wetheril process, the stepof supplying the bed fuel in the form of brlquets, together with thestep of supplying in the working signatures.

charge a briqueted mixture of plumbiferous material and reducing agent;substantially as described.

18. In the production of sublimed lead by the Wetherill process, thestep of supplying the. bed fuel in the form of briquets, said briquetscontaining a percentage of plumbiferous material, together with the stepof supplying in the working charge briqueted plumbiferous material;substantially as described.

19. In the roduction of sublimed lead by the Wetheril process, the stepof supplying the bed fuel in the form of briquets, said briquetscontaining a percentage of plumbi-ferous material, together with thestep of supplying in the Working charge a briqueted mixture ofplumbiferous material and reducin agent; substantially as described.

20. n .a process for volatilizing and oxidizing metal values involvin ofair into a bed containing the metal-bearing material and combustib ematerial under conditions which will leave the worked-off char e as aclinker and which will produce a v0 atile fume, the step of supplying atleast part of the charge in the form of briquets; substantially asdescribed.

21. In the production of sublimed lead in. volving the blowing of airinto a bed con,

I tainin the metal-bearing material and com- FRANK G. BREYER. JAMES A.SINGMASTER, ALBERT E. HALL.

the blowing I

